Cesium 视角太远隐藏实体的label

标红部分代码为视角缩放隐藏

viewer.entities.add({
      id,
      name,
      position: Cesium.Cartesian3.fromDegrees(lon, lat),
      point: {
        pixelSize: size,
        color: Cesium.Color.fromCssColorString(color)
      },
      label: {
        text: name,
        font: '12px sans-serif',
　　　　　　// 
        distanceDisplayCondition: new DistanceDisplayCondition(0, 200000000),
        pixelOffset: new Cesium.Cartesian2(0, -20), // y大小根据行数和字体大小改变
        horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
        backgroundPadding: new Cesium.Cartesian2(5, 5),
        showBackground: true,
        backgroundColor: Cesium.Color.fromCssColorString('rgba(15, 44, 88, .8)')
      }
    })

以下附上api两个参数near far   基本介绍